The following description is provided to assist the understanding of the reader. None of the information provided or references cited is admitted to be prior art to the present invention.
Insect pests that are frequently found in the vicinity of manure and the feces of domestic animals are annoyances and health hazards to the animals themselves and to people around such animals. In particular, flies, such as stable flies, horn flies, house flies, face flies and other flies which breed in manure, are common pests of mammals such as cattle, horses, sheep, goats, swine and poultry. If breeding of such insect pests remains uncontrolled, large numbers may quickly accumulate and may irritate and distress these animals to the degree that the animals become restless, hyperactive, and may even stop feeding temporarily. Distressed animals are also prone to illness and may frequently lose weight. Additionally, such insect pests are also vectors in the dissemination of a number of animal and human diseases and/or parasites. Thus, the control of insect pests is highly desirable, especially with personal or pet animals (such as horses and dogs), and where large numbers of animals are kept, such as on farms, feedlots, shipping yards, and the like.
Customarily, to control flies in barns and other animal shelters, the animals themselves, and their environment in general, are treated with pesticide-containing products. Though usually effective, these methods of control are time-consuming and expensive, especially if they require repetitive applications. Moreover, it is generally very difficult, if not impossible, to effectively treat animal feces and manure with pesticides to completely prevent flies from breeding therein.
A variety of insect growth regulators have successfully been used in the control of insect pests of domestic animals, particularly to control dung-breeding flies, as an alternative to traditional pesticides. Complete inhibition of development in manure has been achieved by administering insect growth regulators to cattle in ground feed (for example, juvenile hormone analogues, Harris et al., J. Econ. Entomol. 66:1099-1102, 1973), mineral blocks (for example, methoprene, in Harris et al., J. Econ. Entomol. 67:384-386, 1974), and drinking water (for example, methoprene, Beadles et al., J. Econ. Entomol. 68:781-785, 1975).
Cyromazine (2-cyclopropylamino-4,6-diamino-s-triazine) was developed as a new class of insect growth regulators derived from azidotriazine herbicides, after it was found to cause death to larvae or deformation to pupae (see, for example, U.S. Pat. No. 4,225,598; and Fridel and McDonell, J. Econ. Entomol. 78:868-873, 1985). U.S. Pat. No. 4,225,598 discloses that treating insect larvae representing the stage of eating and growing with cyromazine or salts thereof results in killing the freshly hatched larvae or preventing adults from hatching from the pupae. The mode of action of cyromazine appears to be distinct from that of classical insecticides, chemosterilants or juvenile hormone analogues, yet still remains uncertain (see, for example, Bel et al., Arch. Ins. Biochem. Physiol. 45:69-78, 2000).
Prior to the present invention, it was believed by those of skill in the art that cyromazine was excreted primarily in urine. Thus, the art has believed that in order to control flies in the vicinity of feces, the feces must be intermixed with urine to achieve insecticidal effectiveness. As such, the use of cyromazine has to date been limited to animals where anatomy, physiology and/or housing conditions inherently result in a mixing of urine and feces.
Cyromazine (also known as CGA-72662) is primarily used as a feed-through larvicide in chicken and as a foliar spray on agricultural crops. It is manufactured and formulated by Novartis under the trademark Larvadex®, developed especially for poultry, and presently marketed for fly control in caged-layer chicken manure. Larvadex® is provided as a 1% premix to be added to the chicken feed to achieve a concentration of 5 ppm in the feed. Because of both chicken anatomy, physiology (all chicken excreta are mixed in the cloaca before deposition), and the conditions under which chicken are housed, cyromazine excreted in chicken urine becomes mixed with manure and bedding, thereby inhibiting development of flies therein.
Efforts have been made to expand the use of cyromazine to other domestic animals. Studies have been performed to administer technical cyromazine to outdoor dairy calf hutches in the range of 0.1-1.0 mg/kg of body weight. Doses of 0.5-1.0 mg/kg were found to prevent the development of immature stages of flies in straw bedding. However, it was found that cyromazine in this system is excreted in calf urine, and thus, the insecticidal amount of cyromazine found in the straw bedding is attributable to saturation of the bedding with urine (see Schmidtmann et al., J. Econ. Entomol. 82:1134-1139, 1989; and Miller et al., J. Econ. Entomol. 89:689-698, 1996).
In another study, cyromazine was applied as a feed-through to fattening porkers to prevent house fly breeding in piggeries. In traditional pens with straw bedding, it was found that some adult flies did develop. The author states that this was probably due to uneven mixing of urine, manure and straw, because cyromazine is excreted mainly with the urine (see Skovmand, Intl. Pest Control 30:10-13, 1988). Thus, any insecticidal effect seen was attributable to cyromazine attaching to manure while draining through manure beds.
In another study, cyromazine added to the feed of mink was ineffective to prevent breeding of house flies (Skovmand and Brandt, Ann. Rep. Danish Pest Infestation Lab. 43-44, 1981). Again the author attributes the ineffectiveness of cyromazine to the fact that the mink urine contained 95% of all cyromazine excreted and the fact that mink tend to urinate and defecate at separate sites. The suggested solution is to ensure a mixing of dung and urine in farm animal houses to achieve effectiveness.
Thus, there remained a need in the art for the control of insect pests by treating animals that physiologically separate urine and feces, and are free to move about such that feces droppings are not confined to the same vicinity as urine. Various attempts to address this need have been made, but frequently involve labor-intensive and time-consuming tasks. For example, droppings and manure can be frequently collected and disposed of to prevent fly breeding. As another example, U.S. Pat. No. 5,707,658 provides a method whereby equine manure is treated with sodium bisulphate at least once a week to reduce flies, again a time-consuming activity. As an alternative, insecticides can be used, but in addition to being time-consuming, such applications (for example, sprays) present toxicity problems and environmental concerns.
Therefore, there still remains a need in the art for a simple method of controlling insect pests in low density animal housing and in the vicinity of isolated feces droppings, which is not associated with an additional time-consuming task to be performed by the owner of the domestic animal producing the waste.